Published October 24, 2015 at 5:40 PM Updated December 7, 2015 at 2:44 PM

The United Nations, founded Oct. 24, 1945, celebrated a major milestone as it officially turned 70 years old. It marked the occasion with a “U.N. Day” concert and a massive project to light up the world’s landmarks in “U.N. Blue.”

More than 300 landmarks across 55 countries were illuminated, from Australia’s Sydney Opera House to the Peace Palace in the Hague, from Jordan’s ancient city of Petra to Egypt’s pyramids of Giza, from Singapore’s Super Trees to the Great Wall of China.

But even as the U.N. celebrates the milestone, it looked back on what it has and hasn’t accomplished over seven decades, and acknowledged that more needs to be done to resolve persistent conflicts, stop extremism, end poverty, and save the planet.

“Over the decades, we have helped to bring freedom to billions, dismantle colonialism, defeat apartheid and defend human rights for all,” U.N. Secretary-General Ban Ki-Moon said. “Our enterprise may not be perfect, but without the United Nations, I can tell you that our world will be a far bleaker place.”

CCTV’s Liling Tan gives us a glimpse into global celebrations starting at the U.N. headquarters in New York.